Device for Tightening Screw Connections

ABSTRACT

A device for tightening a screw connection on a flange connection is provided with a tool carrier movable along the flange connection and provided with a traction drive. A tool is arranged on the tool carrier for tightening the screw connection and rotating the nut relative to the flange connection. A control unit is provided for moving the tool carrier in longitudinal direction of the tool carrier into a working position by traction drive control signals. In the working position, the tool is opposite the screw connection to be tightened. The control unit performs, by tool control signals, tightening of the screw connection and rotating of the nut. The control unit has a travel control module with travel controller for moving the tool carrier into the working position. The travel controller stops the traction drive after a predefined travel length has been reached that is a target variable.

BACKGROUND OF THE INVENTION

The invention relates to a device for tightening screw connections whichare arranged along a flange connection which surrounds, in ring-shapedform, a space and preferably the interior of the tower of a windturbine, and of which each screw connection is made up of a threadedelement and a nut screwed onto the threaded element, and the nut issupported against the flange connection, wherein the device has:

-   -   a tool carrier which is movable along the flange connection and        which is equipped with a preferably electric traction drive,    -   a tool which is arranged on the tool carrier and which serves        for tightening the screw connection and rotating the nut        relative to the flange connection,    -   a control unit which is designed to, by means of traction drive        control signals, move the tool carrier into a working position        in which the tool is situated opposite the screw connection that        is respectively to be tightened, and to control the tightening        of the screw connection and rotation of the nut by means of tool        control signals.

A device having these features is known from EP 2 607 685 B1. Saiddevice serves for tightening screw connections which are arranged in arow along a flange. Each screw connection is made up of a threadedelement and of a nut, which is screwed thereon, wherein the nut issupported against the top side of the flange. The tightening of thescrew connection and rotation of the nut relative to the flange isperformed using a tool arranged on a self-propelled vehicle. In order toposition the tool above the screw connection that is respectively to betightened, the vehicle has a position sensor. On the basis of theposition signals acquired by the sensor, the vehicle with the toolarranged thereon is moved in such a controlled fashion until it isdetermined from the signals that the tool is situated in axial alignmentwith the screw connection axis of the screw connection that isrespectively to be tightened. For this purpose, the position signals ofthe position sensor are processed by control technology into signals forthe drive of the vehicle. The controller is furthermore designed tocontrol the tightening process.

The positioning of the vehicle with evaluation of the signals of theposition sensor is complex from a control aspect owing to the requiredaccuracy. Furthermore, a situation may arise in which the positionsensor, if it is designed for example for sensing structures whichproject upward from the top side of the flange, can be confused byobjects which are not a constituent part of the screw connections. Verygood but thus also expensive sensor technology is thus required.

It is therefore the object of the invention to enable, by means oftechnical measures, carrying out the movement of the tool, which ismovable by means of a controlled traction drive along the flangeconnection, into the next working position in a technically lesscumbersome and nevertheless reliable manner.

SUMMARY OF THE INVENTION

To achieve this object for a device of the aforementioned kind, it isproposed according to the invention that the control unit comprises, formoving to the respective working position of the tool carrier, a travelcontrol module with a travel controller which is designed to stop thetraction drive after a predefined travel length, as target variable, hasbeen reached. The travel controller, which is implemented as a module ofthe control unit, is configured to stop the traction drive, and thusinterrupt the travel of the tool carrier, after a travel variablepredefined in the control unit, as setpoint or target variable, isreached.

With such a device, it is possible for the respectively next workingposition to be reliably moved to even without evaluation of positionsignals of a position sensor. This is because such a sensor operatesreliably only if it is capable of reliably detecting features orstructures that are characteristic of the screw connection to be movedto. Achieving this in an error-free manner requires a high level oftechnical outlay in the sensing electronics used and in the conversioninto travel signals. This type of position determination is also notalways error-free, because structures not belonging to the screwconnection can influence the sensor signal, with the risk that the screwconnection that is to be tightened next not being reliably found.

The described device does not require this type of sensing. Instead, theinvention utilizes the realization that, in the case of ring-shapedflange connections such as are typical for the screw connection of towerportions of a wind turbine, the positions of the screw connections arefixed at the design stage and are therefore known. Using the designdata, it is thus possible with high accuracy to determine at least therelative arrangement of the screw connections with respect to oneanother. This is because the screw connections generally have a spacing,that is to say circumferential spacing, to one another which is alwaysconstant. Once the position of a first screw connection to be tightenedhas been reliably found, the positions of all of the other screwconnections can be calculated on the basis of geometrical relationships,along with, in particular, the travel lengths, that is to say distances,to be covered in the circumferential direction of the flange.

The movement to the next screw connection, which may be either theadjacent screw connection or any other screw connection of the flangeconnection, is thus performed not on the basis of sensor control butrather using a vehicle control method with travel lengths or distancesas target values. For this purpose, the control unit comprises a travelcontrol module with internal travel distance presets, wherein thevehicle control method implemented in the travel control module isconfigured to stop the traction drive after the travel or distancepreset as target variable has been attained, such that, at the workingposition reached at this point in time, the screw connection process canbe initiated, which is likewise performed in a manner dependent onsignals from the control unit.

Since the invention is based on a control method with travel controlutilizing the known geometrical positions of the screw connection axesof all of the screw connections, it is possible in the travel controlmodule to freely program the sequence in which the screw connections aretightened. This is because it is not always advantageous for therespectively adjacent screw connection to be tightened next. It may alsobe advantageous, after the tightening of one nut, for the nut of a screwconnection situated oppositely in relation to the centre of the flangeconnection to be tightened next, and so forth.

Advantageous embodiments of the device are specified in the dependentclaims.

With one refinement, provision is made whereby the tool carrier is, forthe support thereof on the top side of the flange connection, equippedwith rollers which are mounted on horizontal rotary axles on the toolcarrier. The primary object of these rollers is to bear the weight ofthe tool carrier with the tool arranged thereon.

Furthermore, the tool carrier may, for the lateral support thereof, forexample against the inner wall of the tower of the wind turbine, beequipped with additional rollers which are mounted on substantiallyvertical rotary axles on the tool carrier.

Preferably, the tool carrier is, for the lateral guidance thereof,equipped with rigidly attached alignment elements on which there isformed an alignment surface extending in a direction of travel, thesurface normal of which alignment surface is opposite to the directionin which the tool carrier is supported by means of the additionalrollers, that is to say by means of the rollers supported against thevertical inner wall. The alignment surfaces are situated in a plane inwhich they can be supported on the rear sides of the exposed threadedend portions of the screw connections. In this way, the alignmentelements guide the carriage laterally and prevent the carriage fromlaterally departing from its intended travel line. With an action in theopposite direction, that is to say outward, corresponding alignmentelements or alignment surfaces are not necessary. This is because thelateral guidance of the carriage in this direction is already achievedby means of the additional rollers.

The rollers, that is to say those rollers which are mounted onhorizontal rotary axles and those rollers which are mounted onsubstantially vertical rotary axles, do not all need to be driven. Anembodiment is rather preferred in which the rollers are only in partdriven rollers, this applying for example in the case of only a singleroller. The remaining rollers are then non-driven, concomitantlyrotating rollers.

It is advantageous if a roller which bears a particularly large amountof weight is a driven roller. Therefore, with one refinement, it isproposed that each driven roller is one of those rollers which aremounted on horizontal rotary axles.

To simplify the centring of the tool in relation to the screw connectionaxis of the respective screw connection, a further refinement proposes aclutch, preferably an electromagnetic clutch, between the or each drivenroller and a drive motor of the traction drive which drives the roller.If the clutch is separated or deactivated, these rollers of the vehicleare thus also freely rotatable, such that the vehicle can move freelyand with low friction in a direction of travel, and the resulting playsimplifies the centring of the tool on the screw connection axis of therespective screw connection.

With regard to the clutch, the control unit is preferably additionallydesigned to, by means of clutch switching signals, activate and/ordeactivate the clutch.

In order to make the travel control particularly exact and verifiable,it is possible for at least one of the rollers to be, for the rotationalangle coding thereof, coupled in slip-free fashion to an angle encoder.Said angle encoder detects the rotational angle of the roller, fromwhich the exact travel distance covered by the roller can be calculatedin the control unit in order to thus obtain exact values in the travelcontrol for the movement to the next screw connection.

Since driven rollers often operate with a certain degree of slip, it isadvantageous if the rotational-angle-coded roller is not a driven rollerbut rather one of the non-driven rollers.

The rotational-angle-coded roller is preferably one of the additionalrollers which laterally support the tool carrier. The advantage of thisrefinement lies in the fact that, in the tower of a wind turbine, theinner walls are generally of relatively smooth-walled form, such that aroller running on the surface exhibits particularly exact andreproducible angular values.

If the angle encoder is not arranged on the same axle as that on whichthe roller is mounted on the vehicle, the angle encoder should becoupled by means of a chain, or a toothed belt which operates in acorrespondingly slip-free manner, to the rotational-angle-coded roller.Furthermore, the angle encoder is also connected in terms of signaltransmission to the travel control module of the control unit.

The tool carrier that forms the vehicle is preferably equipped with avertical guide by means of which the tool is mounted inheight-adjustable fashion on the tool carrier.

In order to improve the centring of the tool in relation to the screwconnection axis of the respective screw connection, a further refinementprovides a transverse guide with a guide direction transverse withrespect to the longitudinal direction or direction of travel of the toolcarrier. By means of the transverse guide, the vertical guide and/or thetool is mounted in horizontally displaceable fashion on the toolcarrier. Preferably, the transverse guide is designed to exhibitparticularly low friction and is equipped with a spring arrangementwhich acts on the vertical guide or the tool with a restoring force intoa central position.

Also proposed is a documentation module which is preferably combinedwith the control unit in a common housing. In the documentation module,a data set is stored for each tightened screw connection. The data setcomprises

-   -   the individual identifier of the respective screw connection,        wherein the identifier is detected by means of a barcode scan or        an RFID tag at the respective screw connection, or the        identifier is alternatively determined by the position of the        respective screw connection on the flange connection,    -   and/or the actually used tightening force of the tool,    -   and/or the angle of rotation covered by the nut relative to the        flange connection,    -   and/or the measured change in length of the threaded element        during the tightening process.

The tool used in the device may be, for example, an electrically orhydraulically driven screwdriver with a high drive torque. What ispreferable, however, is a method for tightening the screw connectionswhich operates in substantially torsion-free fashion. Such tightening ispermitted if the tool is a screw-tensioning cylinder which operatesaxially in relation to the respective screw connection.

Such screw-tensioning cylinders are known. They commonly operate usinghydraulic force, and are equipped with a cylinder housing, whichsurrounds a hydraulic working chamber, and with an exchangeable socket,which is arranged rotatably in the cylinder housing and which can bescrewed together with a threaded end portion of the screw connection. Afurther constituent part of a screw-tensioning cylinder of the type is arotary sleeve for driving, that is to say rotating, the nut in positivelocking fashion while the threaded element of the screw connection isexpanded slightly by the hydraulic pressure.

In the case of a screw-tensioning cylinder being used as a tool, this isequipped with an electric drive for rotating the exchangeable socket.Furthermore, the screw-tensioning cylinder may be equipped with a secondelectric drive. This is responsible for rotating the rotary sleeve andthus tightening the nut, and is additionally also designed for verticaladjustment of the screw-tensioning cylinder relative to the toolcarrier.

Owing to the large number of screw connections and the requiredpressures of up to 300 bar, it is necessary, for the reliability of theauxiliary assemblies, for these to be designed to be correspondinglydurable and stable, resulting in a high weight.

Therefore, for the exactness of the travel control, it is additionallyadvantageous if the auxiliary assemblies of the device, for example anenergy module, are arranged not on the tool carrier but rather so as tobe spatially separate therefrom. One refinement of the device istherefore characterized by a hydraulic line which leads from a hydraulicpump to the hydraulic working chamber of the screw-tensioning cylinder.The hydraulic pump is separate from the screw-tensioning cylinder andthe vehicle on which the screw-tensioning cylinder is arranged, and thehydraulic pump is arranged in static fashion at one location and is aconstituent part of an energy module.

According to a further embodiment of the device, the control unit isalso arranged on the energy module, and is for example arranged togetherwith the latter on a support. For the transmission of the traction drivecontrol signals and of the tool control signals, an electrical signalline leads from the control unit to the tool carrier, wherein the signalline may be mechanically connected, at least over a part of its length,to the energy supply line.

Also proposed is a pivotable stand with one or more vertical pivot axes,wherein the stand is equipped with fastening means for the positionallyfixed fastening thereof, and a longitudinal portion of the energy supplyline is mounted into the stand.

The pivotable stand is preferably designed to support the energy supplyline over an angle of rotation of at least approximately 360°.

The tool carrier preferably has a leadthrough for the energy supplyline, wherein the leadthrough is situated on a slide which is arrangedmovably on the tool carrier, preferably in a direction of travel of thetool carrier.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and advantages will emerge from the followingdescription of an exemplary embodiment illustrated in the drawing.

FIG. 1 shows a perspective view into two connected-together ring-shapedportions of the tower of a wind turbine, wherein only half of theportions is shown, over that length of the tower in which the portionsare connected by means of a ring-shaped flange connection with amultiplicity of screw connections.

FIG. 2 shows a horizontal section, in this case with the fullcircumference of the ring-shaped tower portions illustrated.

FIG. 3 shows a mobile unit, in the form of a carriage, of the device fortightening screw connections, in a perspective illustration.

FIG. 4 shows a side view of the mobile unit.

FIG. 5 shows the mobile unit in a plan view.

FIG. 6 shows, in a detail illustration, a stand arranged in the mobileunit, including a tool arranged in the stand.

FIG. 7 shows the stand in an end view.

FIG. 8 shows, in a detail illustration, a holding tool, at the lower endof which there is arranged a tool for the counter-holding action duringthe tightening of the screw connection;

FIG. 9 shows the holding tool in a view.

FIG. 10 shows, in a partial section, a hydraulic tool for tighteningscrew connections, wherein the tool is illustrated in a position inwhich it has been lowered to and set down onto the top side of theflange connection.

FIG. 11 shows the lower part of the hydraulic tool in an embodiment inwhich the holding tool is combined with the tool.

FIG. 12 shows the hydraulic tool in yet another embodiment, in which theholding tool is arranged in the centre of the hydraulic tool.

DESCRIPTION OF PREFERRED EMBODIMENTS

The device for tightening screw connections is made up of a mobile unit1, of a spatially separately arranged static unit 2, and of a cableline, in particular a supply and signal cable 3, between the mobile unit1 and the static unit 2. A constituent part of the mobile unit 1 is atool 5 for tightening screw connections. In the exemplary embodimentdescribed in more detail here, the tool is a hydraulically operatedscrew-tensioning cylinder 5. The energy supply of the device is situatedin the static unit 2. A further constituent part of the static unit 2 isan electronic control unit 4, which in turn comprises inter alia atravel control module 4A and a documentation module 4B. In thedocumentation module 4B, a data set is stored for each individualtightened screw connection, which data set thus permits a later check ofthe most important characteristic data of the screw connection process.

The tool 5 is arranged in height-adjustable fashion on a carriage 6which is movable by means of a drive. The carriage 6 is therefore thetool carrier of the device.

The carriage or tool carrier is, by means of rollers mounted thereon,configured for being moved along a ring-shaped flange connection 7,which is a constituent part of a tower-type wind turbine, into differentcircumferential positions in order, at each of these positions, totighten, retighten or else release a screw connection situated there.

The flange connection 7 is in this case a double flange composed of anupper ring-shaped flange 7A and a lower ring-shaped flange 7B which liespreferably areally against the upper ring-shaped flange. The upperring-shaped flange 7A is situated at the lower edge of an upperring-shaped tower portion 8A. The lower ring-shaped flange 7B issituated at the upper edge of a lower tower portion 8B. The towerportions 8A, 8B form, together with further similar tower portions, thevertical tower of a wind turbine. Such wind turbines, with heights of upto 150 m, are composed of tower portions for assembly reasons. Thesetower portions are substantially cylindrical and enclose a circularspace 9, which is surrounded by the flange connection 7. The towerportions may narrow conically in an upward direction.

The tower portions are screwed together by virtue of the ring-shapedflange 7A being formed on the in each case upper tower portion 8A andthe ring-shaped flange 7B being formed on the tower portion 88B arrangedin each case directly therebelow. The flange connection 7 which iscomposed of two ring-shaped flanges is held together by means of amultiplicity of screw connections. These are arranged so as to bedistributed in each case at uniform intervals over the circumference.

Each screw connection 10 is composed of a bolt-like threaded element 11and of a threaded nut 12 which is screwed onto the threaded portion ofthe threaded element 11.

The threaded nut 12 is supported with its bottom side on the preferablyflat top side of the ring-shaped flange 7A.

In the exemplary embodiment, the threaded element 11 is formed so as tobe supported in the manner of a screw with a radially widened collar orhead from below against the lower ring-shaped flange 7B of the flangeconnection 7.

As is conventional in the case of screw connections, a washer mayadditionally be situated between the threaded nut 12 and the upperring-shaped flange 7A.

The screw connections 10 are arranged so as to be distributed uniformly,that is to say at uniform intervals along the flange connection 7,around the space 9. The circumferential spacing of the screw-connectionaxis of one screw connection to the screw-connection axis of theimmediately subsequent screw connection is thus always the same.Therefore, if the radius, in relation to the centre of the space 9, ofthe ring on which the axis of the screw connections 10 are situated isknown, and the total number of screw connections is likewise known, thedistances in the circumferential direction between the axes of the screwconnections can be mathematically determined. These geometricalspecifications are utilized to move the carriage 6 with the tool 5arranged thereon along the extent of the flange 7 into individualworking positions, wherein each working position is distinguished by thefact that the tool 5 is situated above and in alignment with the axis ofthe screw connection 10 that is respectively to be tightened.

The tool 5 used in the device may be a hydraulic torque driver, anelectrical screwdriver or a screw-tensioning cylinder.

In this regard, the variant of the screw-tensioning cylinder will bedescribed in more detail below on the basis of FIG. 10. Saidscrew-tensioning cylinder is distinguished, in particular during theretightening of screw connections, by the fact that a substantiallytorsion-free screw-tensioning process is achieved, that is to saywithout the occurrence of relatively high torsional forces over thescrew length. For this purpose, the nut 12 is not directly rotated witha high tightening torque, the threaded element 11 rather being expandedin its longitudinal direction for example by means of hydraulic forces,whereby the underside of the nut 12 is moved clear of the ring-shapedflange 7A. In the thus expanded state, the nut 12 is retightened with arelatively low torque. Such a screw-tensioning cylinder 5 and such ascrew-tensioning process with elongation of the threaded element 11 willbe described in more detail further below.

All of the screw connections 10 extend with their screw-connection axesat right angles to the top side of the ring-shaped flange 7A andparallel to the central main axis of the tower portions 8A, 8B.

The main element of the mobile unit 1 is the tool carrier 20. In orderthat this can be moved along the flange connection into individualworking positions, the tool carrier 20 is equipped with multiplerollers, which are in some cases driven, and thus propel the toolcarrier 20, and which are in some cases not driven, that is to saymerely roll conjointly during the movement.

In the exemplary embodiment shown here, two rollers 21A, 21B areprovided, by means of which the tool carrier 20 is supported on the topside of the flange connection 7. The rollers 21A, 21B are mounted onhorizontal rotary axles on the tool carrier 20. The roller 21A is adriven roller, whereas the roller 21B is a freely conjointly runningroller. The rollers 21A, 21B bear the predominant part of the weightforces of the tool carrier 20 and of the assemblies arranged thereon,including those of the tool 5. Since the rollers 21A, 21B are subjectedto a high weight loading, it is expedient for at least one of theserollers, in this case the roller 21A, to be the drive roller.

An electric drive motor 24 drives the roller 21A and, together with thelatter, forms the traction drive of the device. The drive motor 24 ofthe traction drive is not seated on the same shaft as the driven roller21A, a toothed belt or a chain rather converting the rotation of thedrive motor 24 into identical, increased-speed or reduced-speed rotationof the drive roller 21A. It is however possible, if there is enoughspace available, for the drive motor 24 to be arranged on the same shaftas the roller 21A. The drive motor 24 of the traction drive receivestraction drive control signals from the control unit 4.

A switchable clutch 25, preferably an electromagnetic clutch, isarranged in the drive path between drive motor 24 and roller 24A. Theclutch 25 receives its clutch switching signals likewise from theelectronic control unit 4. If the clutch 25 is separated or deactivated,the roller 24A is thus made freely rotatable, such that the tool carrier20 can move freely in the direction of travel, and the play that is thuspossible simplifies the centring of the tool 5 relative to thescrew-connection axis of the respective screw connection 10.

Rollers 22 are also mounted on the tool carrier 20, but these aremounted on substantially vertical rotary axles. These additional rollerssupport the carriage against the inner wall 23 of the tower portion. Therollers 22 are subjected to only low weight loading compared with therollers 21A, 21B. Nevertheless, they are supported against the innerwall 23, which is achieved by means of an arrangement of the rollers21A, 21B in which the centre of gravity of the carriage is situatedfurther to the outside than the rolling line of the rollers 21A, 21B.

The additional rollers 22 are not driven, that is to say merely rotateconjointly. It is preferable for at least one of the rollers 22 to becoupled in slip-free fashion to an angular encoder 26. The angularencoder 26 permits the detection of angular signals of the roller. Fromthe angular signals, the processor of the electronic control unit 4calculates the travelling distance of the tool carrier 20 along theinner wall 23. From this, in turn, it is possible, by means of theprocessor, to mathematically determine and check the distances that thetool carrier 20 covers or has covered along the ring on which the screwconnections 10 are arranged.

For the lateral guidance of the carriage 6, an alignment element 30,which is preferably provided twofold, is fastened to the tool carrier 20at the bottom. The alignment element 30 is equipped with an alignmentsurface 30A which extends in the direction of travel and the surfacenormal of which points inward and therefore oppositely to the directionin which the tool carrier is supported by means of the additionalrollers 22. The alignment surfaces 30A are arranged on the carriage 6 atsuch a height that, during operation, they are situated at the height ofthe threaded end portions 11A of the threaded elements 11 and above thenut 12. Said alignment surfaces are furthermore situated slightly to theoutside of the threaded end portions 11A on which they can be supported.This has the result, during the travelling movement of the carriage 6,that the carriage is supported on the rear side of the threaded endportions 11A, such that the carriage 6 cannot inwardly depart from therunning line predefined by the rollers 21A, 21B. In the other direction,that is to say in the outward direction, the additional rollers 22already perform the required lateral guidance of the carriage.

Constituent parts of the driven tool carrier 20 are a lower platform 31and an upper platform 32 which is arranged fixedly relative to the lowerplatform 31. The rollers 21A, 21B are supported below the lower platform31. For easy lifting and transportation of the carriage 6 as a whole,eyelets are fastened to the upper platform 32, into which eyelets acrane hook can be engaged.

A stand 33 which holds the tool 5 is supported on a surface on the topside of the lower platform 31. The stand 33 is formed as a verticalguide 34 for the height adjustment of the tool 5.

On the top side of the platform 31, on the one hand, and on the base ofthe stand 33, on the other hand, there are provided elements of atransverse guide 35 with a guide direction transverse with respect tothe longitudinal direction and thus the direction of travel of the toolcarrier 20. By means of the transverse guide 35, which operates with lowfriction, the stand 33 and thus the tool 5 arranged therein is mounteddisplaceably on the platform 31, specifically so as to be displaceabletransversely with respect to the direction of travel of the toolcarrier.

The sliding action of the stand 33 relative to the platform 31 may besupplemented by a spring arrangement 36 which, in the absence oftransverse forces, holds the stand 33 in a central position in relationto the platform 31. Thus, when no transverse forces act on the tool 5and on the stand 33, the stand, guided by the transverse guide 35 andunder the force of the spring arrangement 36, automatically returns intothe central position.

The stand 33 simultaneously forms a vertical guide 34 for the heightadjustment of the tool 5. For this purpose, the stand is made up of thestand base 41, which lies displaceably on the platform 31 and which isguided in the transverse guide 35, of vertical guide rods 42 which arefastened rigidly to the stand base, of an upper stand frame 49 whichconnects the upper ends of the rods, and of a stand frame 50 which isadjustable in height by motor drive. The stand frame 50, which ismovable up and down, is guided by the guide rods 42 of the verticalguide 34. The tool 5 is fixed to the stand frame 50.

For the tensioning process itself, the tool 5 duly operateshydraulically. For automatic tool operation, however, at least twoelectric drives 51, 52 are also provided. The two drives 51, 52 operatein a manner dependent on tool control signals from the control unit. Thefirst electric drive 51 drives an exchangeable socket which is arrangedrotatably in the screw-tensioning cylinder. Said first electric drive issituated preferably at the top on the cylinder housing of thescrew-tensioning cylinder. The second electric drive 52 is arrangedlower down and preferably on the height-adjustable stand frame 50.

The second electric drive 52 drives a rotary sleeve by means of whichthe threaded nut 12 can be set in rotation by means of a positivelylocking action. The second drive 52 may additionally be designed toraise and lower the stand frame 50 and thus the tool 5 relative to thestand 33, which in the exemplary embodiment is realized by means of ascrew drive 56 arranged parallel to the guide rods 42, to which screwdrive the drive shaft of the second drive 52 can be coupled.

The second drive 52 therefore has two functions. In a manner dependenton corresponding tool control signals from the control unit, the seconddrive can be coupled either to the rotary sleeve or to the screw drive56.

During the tightening, retightening or else loosening of the screwconnections 10, it is possible in principle for a situation to arise inwhich the threaded elements 11 conjointly rotate in an undesired manner.To prevent this during the tensioning process, on the tool carrier 20,there is arranged not only the tightening tool but also a holding tool70 which serves as counter-holder. A constituent part of the holdingtool 70 is at least one counter-holding surface 75 which can besupported against a surface on the radially widened portion of thethreaded element 11, for example against the surface of a hexagon withwhich the threaded element 11 is equipped below the flange connection 7.The positive locking that is thus realized prevents the conjointrotation of the threaded element 11 during the tightening, retighteningor loosening of the screw connection 10.

In order to bring the counter-holding surface 75 into engagement withthe surface on the radially widened portion of the threaded element 11,an electric drive 77 is arranged on the lower platform 31 for thepurposes of moving the holding tool 70 back and forth between a passiveposition and an active position, the counter-holding position. It isonly in the active position that the counter-holding surface 75 abutsagainst the corresponding surface and in particular hexagonal surface ofthe threaded element 11. The processor of the control unit 4 isconfigured to control the electric drive 77 by means of holding toolcontrol signals.

In the embodiment illustrated, the tool portion 79 of the holding tool70 is configured in the manner of an open-ended spanner with twomutually parallel counter-holding surfaces 75 arranged opposite oneanother.

Here, the drive 77 of the holding tool 70 operates transversely withrespect to the axis of the screw connections. The drive 77 for movingthe holding tool 70 back and forth is, in the embodiment described here,in the form of a toothed-rack drive. Alternatively, it is possible, in amanner not illustrated in the drawing, for the drive of the holding toolto operate parallel to the axis of the screw connection 10, that is tosay vertically.

The holding tool 70 comprises a tool main body 78, which is connected ata drive side to the drive 77, and the tool portion 79, with thecounter-holding surfaces 75 formed thereon. The tool portion 79 isguided on the tool main body 78 so as to be movable counter to the forceof a spring 80. Therefore, if the holding tool 70 is moved against thethreaded element 11, the spring 80 holds the tool portion 79 back untilthe parts have assumed the rotational position relative to one anotherwhich permits the positive locking action. This is because, as a resultof a relative rotation of the parts involved, at some point in time arotational position is reached in which the counter-holding surfaces 75can latch securely and in positively locking fashion under springpressure and, in so doing, enter into engagement.

When the tool portion 79 is not under load, that is to say in theabsence of abutment or positive locking on the threaded element, thetool portion 79 is supported, under the force of the spring 80, againsta stop 81 which is situated on the tool main body 78.

Since the rollers 21A, 21B define a standing plane E of the carriage orof the tool carrier 20, the drive 77 of the holding tool 70 is situatedabove the standing plane E, wherein the drive is preferably fastened tothe platform 31. From there, the tool main body 78 extends down beyondthe standing plane E to the tool portion 79. Said tool portion issituated at a level below the flange connection 7.

The length of the tool main body 78 and thus the basic position of thetool portion 79 can be manually set. The position thus set is secured bymeans of a clamping screw.

The drive 77 of the holding tool 70 is also controlled by means ofcontrol signals from the control unit 4, specifically by means ofholding tool control signals. The control is such that the holding tool70 is moved from its rest position into its active position at theearliest when the tool carrier 20 has assumed a working position inwhich the axis of the tool 5 is aligned with the axis of the respectivethreaded element 11.

During the practical operation of the device, the static unit 2 ispositioned spatially separately from the mobile unit 1, that is to saythe carriage, at a suitable location within the space 9. This locationmay for example be an intermediate floor or may be a fixedly installedladder for service personnel, which ladder connects individual levels ofthe tower. It is however preferable for the static unit 2 to be arrangedas far as possible centrally within the space 9. It is thereforenecessary to connect the assemblies and devices of the static unit 2 tothe carriage 6 by means of the suitable supply and signal cable 3. Thestatic unit 2 includes, for example, an energy module 88 or energymodules for the supply of energy to the traction drive, to the tool 5including all of its functions, and to the holding tool 70.

The control unit 4 is also a constituent part of the static unit 2. Thecontrol unit 4 is designed inter alia to, by means of traction drivecontrol signals, move the tool carrier 20 in the longitudinal directionof the tool carrier 20 into a working position in which the tool 5 issituated opposite the screw connection that is respectively to betightened, and, by means of tool control signals, perform the tighteningof the screw connection and rotation of the nut.

The control unit 4 is preferably arranged on the energy module 88 orarranged together with the latter on a support. In the embodiment as perFIGS. 1 and 2, the static unit 2 is combined to form a box. Rollersunder the box and handles on the box make it easier for the box to behandled during transport.

For the supply of energy, energy supply lines lead from the energymodule 88 to the tool carrier 20. These include, for example, electricalcables for the supply of electricity to the various electric drives ofthe tool carrier 20, of the tool 5 and of the holding tool 70. Anelectrical current distributor may also be a constituent part of theenergy module 88.

The supply cables furthermore include a hydraulic line 87 for the supplyto the hydraulically driven tool 5. The associated hydraulic pump 86 isalso a constituent part of the static unit 2.

For the transmission of the traction drive control signals, of the toolcontrol signals, of the holding tool control signals and of the clutchswitching signals, there is furthermore at least one signal line betweenthe control unit 4 and the tool carrier 20. The signal connection mayhowever also be cable-free or wireless.

Said lines, which are combined as a supply and signal cable 3, betweenthe static unit 2 and the carriage 6 are, where possible and at leastover a part of their length, led in parallel and in mechanicallyconnected-together fashion.

For the guidance of the cable 3, a constituent part of the device is apivot stand 95, which is installed as far as possible centrally in thespace 9, with one or more vertical pivot axes. The pivot stand 95 is,for the fastening thereof within the space 9, equipped with fasteningmeans, for example brackets that can be screwed on. The supply andsignal cable 3 is mounted into the pivot stand 95. Said pivot stand isdesigned to support the cable 3 within the space 9 over a rotationalangle of at least approximately 360°, such that the cable 3 can followthe movement of the carriage 6 over the entire circumference of theflange.

In order that fixtures and obstructions in the space 9 do not impede themovement of the cable 3 over the full 360°, a facility is provided onthe tool carrier 20 for that portion of the supply and signal cable 3which ends there to be displaced relative to the tool carrier 20 in thedirection of travel. For this purpose, the tool carrier 20 is equipped,on its upper platform 32, with a slide 96 which is movable in thedirection of travel of the tool carrier 20. The slide 96 is equippedwith an opening through which the cable 3 passes into the interior ofthe carriage or tool carrier 20. The slide 96 with the opening is freelymovable such that, depending on the position of the slide, the cable 3leads into the interior of the carriage further towards the front orfurther towards the rear.

FIG. 10 shows the hydraulically operated screw-tensioning cylinder 5,which forms the tool in this case and which serves for the tightening,in particular retightening, and possibly also the loosening, of thescrew connections 10 shown in FIGS. 1 and 2. The screw-tensioningcylinder is illustrated in its operating position before the applicationof hydraulic pressure. In this position, the screw-tensioning cylinderhas been lowered to such an extent that it is supported with its bottomside 102 on the ring-shaped flange 7A.

With the screw-tensioning cylinder 5, a predefined preload force can beapplied to the threaded element 11 in the bolt longitudinal direction,whereby the threaded element 11 expands slightly in order, in thisstate, for the threaded nut 12 of the screw connection to be tightenedor retightened.

An exchangeable socket 114 arranged rotatably in a cylinder housing 100of the screw-tensioning cylinder 5 is equipped, at one end thereof, withan internal thread 116. By means of this thread, the exchangeable socket114 is, before the start of the tensioning process, screwed by rotationof the exchangeable socket 114 onto that free threaded end portion 11Aof the threaded element 11 which projects upward beyond the nut 12. Thisscrewing-on of the exchangeable socket 114 is also associated with acorresponding lowering of the screw-tensioning cylinder 5 as a whole,until the bottom side 102 comes to lie on the ring-shaped flange 7A,because the exchangeable socket has no or only little longitudinal playrelative to the cylinder housing 100.

Subsequently, the exchangeable socket 114 that has thus been screwedtogether with the threaded element 11 is hydraulically placed undertension, whereby the screw connection expands in a longitudinaldirection. The contact surface 12A of the threaded nut 12 thus movesclear, such that the threaded nut 12 can then be rotated with onlylittle rotational resistance and, in this way, tightened or retightenedagainst the underlying surface, that is to say against the ring-shapedflange 7A and possibly against a washer.

The hydraulic tensioning mechanism is situated in the pressure-tightcylinder housing 100. This may also be assembled in modular fashion frommultiple cylinder portions. The rigid continuation of the cylinderhousing 100 is a support tube 101. This itself is either part of thecylinder housing 100, as illustrated, or a separate component. Thesupport tube 101 is open towards the screw connection, surrounds thethreaded nut 12, and is supported with the bottom side 102 against thetop side of the ring-shaped flange 7A. Said top side therefore forms thecounterbearing during the tightening process. The tightening process isperformed by virtue of the exchangeable socket 114 pulling on thethreaded end portion 11A, wherein, for the retightening of the nut 12,the latter is screwed downward until it comes to bear with its contactsurface 12A firmly against the flange 7A again.

The support tube 101 is equipped with at least one opening which is ofsuch a size that the nut 12 can be rotated, and thus retightened,through the opening. This is self-evidently possible only if thetensioning device is operating at the same time, and therefore the nut12 is not subjected to considerable friction loading. The rotation ofthe threaded nut 12 is performed by means of a rotary sleeve 110 whichsurrounds the nut. The rotary sleeve 110 is driven by a gearing 111,which is attached laterally to the support tube 101 and which operatesthrough the opening thereof.

The cylinder housing 100 is equipped with a hydraulic port 112 via whicha hydraulic working chamber 118 in the interior of the tool is connectedvia the flexible but pressure-tight hydraulic line 87 to a hydraulicpump 86 (FIG. 1). The hydraulic pump 86 is a constituent part of thestatic unit 2.

Via the hydraulic port 112, highly pressurized hydraulic fluid passesinto the working chamber 118, whereby a piston 115 which is mounted inlongitudinally movable fashion in the cylinder housing 100 can be actedon with hydraulic pressure. As a result of the build-up of hydraulicforce in the hydraulic working chamber 118, the piston 115 is pushedupward. This is performed counter to the force of a spring 117 whichacts on the piston 115. The spring 117 serves as a piston restoringspring and directly subjects the piston 115 to a force which seeks tohold the piston in its basic position, in which the hydraulic workingchamber 118 has its smallest volume.

The piston 115 surrounds the exchangeable socket 114 in the ring-shapedform. The piston 115 is equipped, at its inner edge, with an encirclingstep which forms a driver surface 121 on which the exchangeable socket114 is supported by way of a radially widened portion 125. Theexchangeable socket 114 can thus be driven by the piston 115. In theabsence of pressure loading, the exchangeable socket 114 is freelyrotatable relative to the piston 115 and relative to the cylinderhousing 100.

The exchangeable socket 114 is, like the piston 115, situated centrallyon the longitudinal axis of the cylinder housing 100, and is made up ofa portion with the internal thread 116, which is screwed onto thethreaded end portion 11A of the threaded element 11, of the radiallywidened portion 125, and of a drive portion 126, in the stated sequence.The drive portion 126 is situated on that end of the exchangeable socket114 which is averted from the threaded element 11.

The drive portion 126 is engaged on by the shaft of the electric drive51, which is operated in a manner dependent on tool control signals fromthe control unit, in order to rotate the exchangeable socket 114 andeither screw this onto the threaded end portion 11A before thetensioning process, with the entire cylinder housing 100 being lowered,or to unscrew the exchangeable socket from the threaded end portion 11Aafter the tensioning process, with the entire cylinder housing 100 beingraised.

If a more extensive height adjustment, that is to say a heightadjustment that cannot be realized merely by means of the rotation ofthe exchangeable socket 114, of the cylinder housing 100 is requiredbefore and after the tensioning process, this additional heightadjustment is performed by means of the electrically driven verticalguide 34. This, too, operates in a manner dependent on control signals,specifically tool control signals, from the control unit 4.

Only when the exchangeable socket 114 has been screwed onto the threadedend portion 11A is the hydraulic tensioning process started by means ofthe control unit 4 by virtue of the hydraulic pump 86 building uphydraulic pressure on the basis of hydraulics control signals from thecontrol unit 4.

The controlled, motor-driven screwing-on and unscrewing of theexchangeable socket 114 is also performed in a manner dependent on toolcontrol signals from the control unit 4.

FIG. 11 shows an embodiment in which the holding tool 70, which impartsa securing action for preventing conjoint rotation, and the tool 5 arearranged in combined fashion on the carriage or the tool carrier.

The holding tool 70 is fastened to the tool carrier 20, in this case tothe lower platform 31 thereof, and comprises two clamping jaws 130 whichare movable toward one another in alignment with the screw-connectionaxis. The ends of the clamping jaws are formed here by thecounter-holding surfaces 75A, 75B, and are for this purpose designed asshells. The radius of the shells is substantially equal to the radius ofthe threaded portion 11A of the threaded element 11.

The two clamping jaws 130 are driven electrically, wherein, again, thecontrol unit 4 (FIG. 1) is configured to control this driving action bymeans of the holding tool control signals. In order that, in thisembodiment, the counter-holding surfaces 75A, 75B press directly ontothe threaded portion, the drive of the holding tool 70 must generaterelatively high pressure forces. In order, here, to additionallyincrease the friction resistance, the counter-holding surfaces 75A, 75Bmay have a suitable friction lining, for example rubber, or a suitablenon-smooth surface. For example, the surface may be adapted in terms ofits structure to the outer structure of the thread such that substantialblocking for preventing conjoint rotation is realized.

The clamping jaws 130 of the holding tool 70 extend through openings 131in the tool 5, wherein the counter-holding surfaces 75A, 75B aresituated within the tool 5. The clamping jaws 130 are guided in theholding tool 70, which is mounted fixedly on the tool carrier, such thatthe clamping jaws are movable, by means of the drive, exclusively intheir clamping direction.

The openings 131 are situated in the support tube 101 of the tool 5.They extend continuously to the bottom side 102 of the support tube 101.It is thus ensured that the tool 5, when it is lowered for thetensioning process, is not impeded by the components of the holding tool70. The tool 5 and the holding tool 70 are duly structurally combined,but their functions are separate from one another.

The embodiment of FIG. 11 makes use of the fact that, in practice, thereis often still a thread longitudinal portion of approximately 5 mmavailable between the top side of the nut 12 and that threaded endportion 11A which is surrounded by the exchangeable socket 114. Thisthread longitudinal portion is sufficient for the conjoint rotation ofthe threaded element 11 to be prevented by means of the clamping jaws130 which are moved together there.

In the embodiment as per FIG. 11, too, the control unit 4 (FIG. 1) maybe configured to, by means of traction drive control signals, move thetool carrier 20 including the screw-tensioning cylinder 5 into a workingposition in which the screw-tensioning cylinder 5 is situated oppositethe screw connection that is respectively to be tightened, and, by meansof tool control signals, control the axial tightening of the screwconnection and the rotation of the nut 12. The control unit 4 (FIG. 1)is additionally designed to, by means of holding tool control signals,control the drive of the holding tool 70.

FIG. 12 shows a further embodiment. In this, the holding tool 70, whichimparts a securing action for preventing conjoint rotation, is arrangedcentrally in the tool 5 formed as screw-tensioning cylinder. Thescrew-tensioning cylinder itself corresponds in terms of its basicconstruction to the embodiment as per FIG. 10 or FIG. 11. This appliesto the cylinder housing 100, to the piston guided therein, which ishowever in this case a double piston 115, to the exchangeable socket 114which is rotatable in the cylinder housing, and to the rotary sleeve 110which is arranged rotatably in the cylinder housing and which serves forrotating the nut 12.

In FIG. 12, on the longitudinal axis of the exchangeable socket 114,there is arranged a rod 140, for which purpose the exchangeable socket114 is equipped with a corresponding longitudinal bore. The single-partor multi-part rod 140 is equipped, at its lower end in FIG. 12, with theholding tool 70, and is equipped, in the region of its upper end in FIG.12, with a rotation-preventing securing means 141. Therotation-preventing securing means 141 holds the rod 140 rotationallyfixed relative to the cylinder housing 100. In the exemplary embodiment,this is achieved by virtue of a bolt 142 which is fixed with respect tothe housing engaging into a longitudinal groove 143 in the rod 140. Thelongitudinal groove 143 extends axially only over a part of the lengthof the rod 140.

The embodiment of FIG. 12 is suitable for screw connections in the caseof which the threaded element 11 is additionally equipped, on the faceside of its threaded end portion 11A, with a polygon 11B. The polygon11B is in this case an axially projecting square, though may also be forexample a hexagon or a square socket or hexagonal socket formed inrecessed fashion in the threaded end portion 11A.

The holding tool 70 is designed as a corresponding polygon, that is tosay in this case as a square socket, which can be coupled to the polygon11B by positive locking. To form the holding tool 70, the lower end ofthe rod 140 is correspondingly enlarged.

The holding tool 70 is supported axially, and under permanent springforce, against the polygon 11B. The spring force is imparted by a springelement 147, which is supported at one side against the holding tool 70or the rod 140 and at the other side against the exchangeable socket114. The spring element 147 serves to provide a permanent axial preloadforce of the holding tool 70, such that a secure engagement of theholding tool 70 on the polygon 11B occurs already after a short relativerotation. The axial clearance required for this purpose is ensured bythe length of the longitudinal groove 143.

A further constituent part of the tool 5 in FIG. 12 is the drive 51 forrotating the exchangeable socket 114. The drive is however realized notcentrally on the longitudinal axis, because the rod 140 is situatedthere. The drive 51 is rather situated with a lateral offset, wherein agearing 148 is provided in the drive path between drive 51 andexchangeable socket 114. A constituent part of the gearing 148 is atoothed gear 149 which is rotationally conjoint with respect to theexchangeable socket 114. The toothed gear 149 has a passage opening 150through which the rod 140 extends in freely rotatable fashion.

It is also the case in the embodiment as per FIG. 12 that the controlunit 4 (FIG. 1) may be configured to, by means of traction drive controlsignals, move the tool carrier 20 including the screw-tensioningcylinder 5 into a working position in which the screw-tensioningcylinder 5 is situated opposite the screw connection that isrespectively to be tightened. Furthermore, the control unit 4 may beconfigured to, by means of tool control signals, control the axialtightening of the screw connection and the rotation of the nut 12.

Furthermore, it is also the case in the embodiment as per FIG. 12 thatthe control unit 4 (FIG. 1) may be configured to, by means of holdingtool control signals and a corresponding drive, control the holding tool70 by virtue of the rod 140 with the holding tool 70 arranged rigidlythereon being lowered in controlled fashion onto the screw connection,and raised again in controlled fashion, by means of the drive. Thefunction of the controlled lowering and raising of the holding tool mayhowever also be performed by the spring element 147.

The specification incorporates by reference the entire disclosure ofGerman priority document 10 2018 107 653.3 having a filing date of 29Mar. 2018.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the inventive principles, it will beunderstood that the invention may be embodied otherwise withoutdeparting from such principles.

LIST OF REFERENCE CHARACTERS

-   1 Mobile unit-   2 Static unit-   3 Cable, supply and signal cable-   4 Control unit-   4A Travel control module-   4B Documentation module-   5 Tool, screw-tensioning cylinder-   6 Carriage-   7 Flange connection-   7A Ring-shaped flange-   7B Ring-shaped flange-   8A Tower portion-   8B Tower portion-   9 Space-   10 Screw connection-   11 Threaded element-   11A Threaded end portion-   11B Polygon-   12 Nut-   12A Contact surface of the nut-   20 Tool carrier-   21A Roller, driven-   21B Roller-   22 Roller-   23 Inner wall-   24 Drive motor-   25 Clutch-   26 Angular encoder-   30 Alignment element-   30A Alignment surface-   31 Lower platform-   32 Upper platform-   33 Stand-   34 Vertical guide-   35 Transverse guide-   36 Spring arrangement-   41 Stand base-   42 Guide rod-   49 Upper stand frame-   50 Stand frame, height-adjustable-   51 Electric drive-   52 Electric drive-   56 Screw drive-   70 Holding tool-   75 Counter-holding surface-   75A Counter-holding surface-   75B Counter-holding surface-   77 Drive-   78 Tool main body-   79 Tool portion-   80 Spring-   86 Hydraulic pump-   87 Hydraulic line-   88 Energy module-   95 Pivot stand-   96 Slide-   100 Cylinder housing-   101 Support tube-   102 Bottom side-   110 Rotary sleeve-   111 Gearing-   112 Hydraulic port-   113 Cone on bolt-   114 Exchangeable socket-   115 Piston-   116 Internal thread-   117 Spring-   118 Hydraulic working chamber-   121 Driver surface-   125 Radially widened portion-   126 Drive portion-   130 Clamping jaw-   131 Opening-   140 Rod-   141 Rotation-preventing securing means-   142 Bolt-   143 Longitudinal groove-   147 Spring element-   148 Gearing-   149 Toothed gear-   150 Passage opening-   E Standing surface-   N Surface normal

What is claimed is:
 1. A device for tightening a screw connection (10)arranged along a flange connection (7), the flange connection (7)surrounding in a ring-shaped form a space, wherein the screw connection(10) comprises a threaded element (11) and a nut (12) screwed onto thethreaded element (11), wherein the nut (12) is supported against theflange connection (7); the device comprising: a tool carrier (20)movable along the flange connection (7) and comprising a traction drive,a tool (5) arranged on the tool carrier (20) and configured to tightenthe screw connection (10) and to rotate the nut (12) relative to theflange connection (7), a control unit (4) configured to move the toolcarrier (20) in a longitudinal direction of the tool carrier (20) into aworking position by traction drive control signals, wherein in theworking position the tool (5) is situated opposite the screw connection(10) to be tightened, and further configured to perform, by tool controlsignals, tightening of the screw connection (10) and rotating of the nut(12), wherein the control unit (4) comprises a travel control module(4A) with a travel controller for moving the tool carrier (20) into theworking position, wherein the travel controller is configured to stopthe traction drive after a predefined travel length has been reached,wherein the predefined travel length is a target variable.
 2. The deviceaccording to claim 1, further comprising first rollers (21A, 21B)configured to support the tool carrier (20) on the flange connection(7), wherein the first rollers (21A, 21B) are mounted with horizontalrotary axles on the tool carrier (20).
 3. The device according to claim2, further comprising second rollers (22) mounted with substantiallyvertical rotary axles on the tool carrier (20), wherein the secondrollers (22) are configured to laterally support the tool carrier (20).4. The device according to claim 3, wherein the tool carrier (20)comprises rigidly attached alignment elements (30) each comprising analignment surface (30A) extending in a direction of travel of the toolcarrier (20), wherein the alignment elements (30) are configured toprovide a lateral guidance for the tool carrier (20), wherein thealignment surface (30A) has a surface normal (N) extending opposite to adirection of a supporting action for the tool carrier (20) provided bythe second rollers (22).
 5. The device according to claim 3, whereinsome of the first and second rollers (21A, 21B, 22) are driven rollersdriven by the traction drive and some of the first and second rollers(21A, 21B, 22) are non-driven rollers.
 6. The device according to claim5, wherein each one of the driven rollers (21A) is mounted horizontally.7. The device according to claim 5, further comprising a clutch (25)connected between each one of the driven rollers (21A) and a drive motor(24) of the traction drive.
 8. The device according to claim 7, whereinthe control unit (4) is configured to activate and/or deactivate theclutch (25) by clutch switching signals.
 9. The device according toclaim 8, wherein at least one of the first and second rollers (21A, 21B,22) is coupled, free of slip, to an angle encoder (26) providingrotational angle coding.
 10. The device according to claim 9, whereinthe at least one of the first and second rollers (21A, 21B, 22) coupledto the angle encoder (26) is one of the non-driven rollers.
 11. Thedevice according to claim 10, wherein the at least one of the first andsecond rollers (21A, 21B, 22) coupled to the angle encoder (26) is oneof the second rollers (22).
 12. The device according to claim 9, whereinthe angle encoder (26) is coupled by a chain or a toothed belt to the atleast one of the first and second rollers (21A, 21B, 22).
 13. The deviceaccording to claim 9, wherein the angle encoder (26) is connected to thetravel control module (4A) of the control unit (4) so as to enablesignal transmission to the travel control module (4A).
 14. The deviceaccording to claim 1, further comprising a vertical guide (34) disposedon the tool carrier (20), wherein the tool (5) is mounted on thevertical guide (34) so as to be height-adjustable relative to the toolcarrier (20).
 15. The device according to claim 14, further comprising atransverse guide (35) comprising a guiding direction transverse relativeto a longitudinal direction of the tool carrier (20), wherein thevertical guide (34) and/or the tool (5) is mounted on the transverseguide (36) so as to be displaceable relative to the tool carrier (20).16. The device according to claim 15, wherein the transverse guide (35)comprises a spring arrangement (36) acting on the vertical guide (34) oron the tool (5) with a restoring force forcing the vertical guide (34)or the tool (5) into a central position relative to a platform (31) ofthe tool carrier (20).
 17. The device according to claim 1, furthercomprising a documentation module (4B) configured to store a data setfor each tightened screw connection, wherein the data set comprises oneor more of the following parameters a) to c): a) an individualidentifier of the respective screw connection (10) and/or of theposition of the respective screw connection (10) on the flangeconnection (7), b) a tightening force of the tool (5) used fortightening the respective screw connection, c) an angle of rotationcovered by the nut (12) relative to the flange connection (7).
 18. Thedevice according to claim 17, wherein the control unit (4) and thedocumentation module (4B) are disposed together in a common housing. 19.The device according to claim 1, wherein the tool is a screw-tensioningcylinder (5) operating axially relative to the screw connection, whereinthe screw-tensioning cylinder (5) comprises: a cylinder housing (100)surrounding a hydraulic working chamber (118); an exchangeable socket(114) rotatable in the cylinder housing (100) by a first electric drive(51); and a rotary sleeve (101) configured to be placed on the nut (12)of the screw connection (10) with a positive locking action.
 20. Thedevice according to claim 19, wherein the screw-tensioning cylinder (5)further comprises a second electric drive (52) operatively connected tothe rotary sleeve (110), wherein the second electric drive (52) isadditionally configured to vertically adjust the screw-tensioningcylinder (5) relative to the tool carrier (20).
 21. The device accordingto claim 19, further comprising a hydraulic pump (86), positionedspatially separated from the tool carrier (20), and a hydraulic line(87) connecting the hydraulic pump (86) to the hydraulic working chamber(118) of the screw-tensioning cylinder (5), wherein the hydraulic line(87) is flexible at least over a part of a length thereof.
 22. Thedevice according to claim 21, further comprising a pivotable stand (95)with one or more vertical pivot axes, wherein the stand (95) is equippedwith fastening means for fastening the pivotable stand (95), and whereina longitudinal portion of the hydraulic line (87) is mounted on thestand (95).
 23. The device according to claim 22, wherein the pivotablestand (95) is configured to support the hydraulic line over an angle ofrotation of approximately 360°.
 24. The device according to claim 21,further comprising a slide (96) arranged movably on the tool carrier(20), wherein the slide (96) comprises a leadthrough for the hydraulicline (87), wherein the slide (96) is configured to move in a directionof travel of the tool carrier (20).
 25. The device according to claim 1,further comprising an energy module (88), positioned spatially separatedfrom the tool carrier (20), wherein the energy module (88) is configuredto supply energy to the traction drive and to the tool (5), wherein anenergy supply line connects the energy module (88) to the tool carrier(20), wherein the energy supply line is flexible at least over a part ofa length thereof.
 26. The device according to claim 25, wherein thecontrol unit (4) is arranged on the energy module (88) or is arrangedtogether with the energy module (88) on a support, wherein, fortransmitting the traction drive control signals and the tool controlsignals, an electrical signal line connects the control unit (4) to thetool carrier (20), and wherein the electrical signal line ismechanically connected, at least over a part of a length thereof, to theenergy supply line.
 27. The device according to claim 25, furthercomprising a pivotable stand (95) with one or more vertical pivot axes,wherein the stand (95) is equipped with fastening means for fasteningthe pivotable stand (95), and wherein a longitudinal portion of theenergy supply line is mounted on the stand (95).
 28. The deviceaccording to claim 27, wherein the pivotable stand (95) is configured tosupport the energy supply line over an angle of rotation ofapproximately 360°.
 29. The device according to claim 25, furthercomprising a slide (96) arranged movably on the tool carrier (20),wherein the slide (96) comprises a leadthrough for the energy supplyline, wherein the slide (96) is configured to move in a direction oftravel of the tool carrier (20).